neo4j-driver-java-skill

<dependency>
    <groupId>org.neo4j.driver</groupId>
    <artifactId>neo4j-java-driver</artifactId>
    <version>6.0.5</version>
</dependency>

implementation 'org.neo4j.driver:neo4j-java-driver:6.0.5'

String uri      = System.getenv().getOrDefault("NEO4J_URI",      "neo4j://localhost:7687");
String user     = System.getenv().getOrDefault("NEO4J_USERNAME",  "neo4j");
String password = System.getenv().getOrDefault("NEO4J_PASSWORD",  "");
String database = System.getenv().getOrDefault("NEO4J_DATABASE",  "neo4j");

spring.neo4j.uri=neo4j+s://xxx.databases.neo4j.io
spring.neo4j.authentication.username=neo4j
spring.neo4j.authentication.password=secret

// Long-lived singleton
var driver = GraphDatabase.driver(
    "neo4j+s://xxx.databases.neo4j.io",          // Aura TLS+routing
    AuthTokens.basic(user, password));
driver.verifyConnectivity();                      // fail fast

// Short-lived (tests / CLI)
try (var driver = GraphDatabase.driver(uri, AuthTokens.basic(user, password))) {
    driver.verifyConnectivity();
    // ...
}

// Read — route to replicas
var result = driver.executableQuery("""
        MATCH (p:Person {name: $name})-[:KNOWS]->(friend)
        RETURN friend.name AS name
        """)
    .withParameters(Map.of("name", "Alice"))
    .withConfig(QueryConfig.builder()
        .withDatabase("neo4j")            // always specify — avoids home-db round-trip
        .withRouting(RoutingControl.READ)
        .build())
    .execute();

result.records().forEach(r -> System.out.println(r.get("name").asString()));
long ms = result.summary().resultAvailableAfter(TimeUnit.MILLISECONDS);

// Write
driver.executableQuery("CREATE (p:Person {name: $name, age: $age})")
    .withParameters(Map.of("name", "Bob", "age", 30))
    .withConfig(QueryConfig.builder().withDatabase("neo4j").build())
    .execute();

try (var session = driver.session(SessionConfig.builder()
        .withDatabase("neo4j").build())) {

    // Read → replica routing
    var names = session.executeRead(tx -> {
        var result = tx.run(
            "MATCH (p:Person) WHERE p.name STARTS WITH $prefix RETURN p.name AS name",
            Map.of("prefix", "Al"));
        return result.stream().map(r -> r.get("name").asString()).toList(); // collect INSIDE
    });

    // Write → leader routing
    session.executeWriteWithoutResult(tx ->
        tx.run("CREATE (p:Person {name: $name})", Map.of("name", "Carol"))
    );
}

// ❌ Returns Result — already closed by the time caller uses it
var result = session.executeRead(tx ->
    tx.run("MATCH (p:Person) RETURN p.name AS name"));
result.stream().forEach(...); // throws ResultConsumedException

// ✅ Collect to List inside callback
var names = session.executeRead(tx ->
    tx.run("MATCH (p:Person) RETURN p.name AS name")
      .stream().map(r -> r.get("name").asString()).toList());

var config = TransactionConfig.builder()
    .withTimeout(Duration.ofSeconds(5))
    .withMetadata(Map.of("app", "myService", "user", userId))  // visible in SHOW TRANSACTIONS
    .build();
session.executeRead(tx -> { /* ... */ }, config);

try (var session = driver.session(SessionConfig.builder().withDatabase("neo4j").build())) {
    var tx = session.beginTransaction();
    try {
        doPartA(tx);
        doPartB(tx);
        tx.commit();
    } catch (Exception e) {
        try { tx.rollback(); } catch (Exception rb) { e.addSuppressed(rb); }
        throw e;
    }
}

try {
    driver.executableQuery("...").execute();
} catch (ServiceUnavailableException e) {
    // No servers — check connection
} catch (SessionExpiredException e) {
    // Server closed session — open new one
} catch (TransientException e) {
    // Managed txns retry automatically; explicit txns need manual retry
} catch (Neo4jException e) {
    // Cypher/constraint error — e.code() gives GQL status code
}

var record = result.records().get(0);
String name = record.get("name").asString();
long age    = record.get("age").asLong();

var node = record.get("p").asNode();
String label = node.labels().iterator().next();
Map<String,Object> props = node.asMap();

// Graph null — use default overload (safe only if key is always projected):
String city = record.get("city").asString("Unknown");

// Absent key — check containsKey first:
if (record.containsKey("city") && !record.get("city").isNull()) {
    String city = record.get("city").asString();
}

// Domain record — field names match RETURN aliases (case-sensitive)
public record Person(String name, long age) {}

// Map single record
var person = driver.executableQuery("MATCH (p:Person {name: $name}) RETURN p.name AS name, p.age AS age")
    .withParameters(Map.of("name", "Alice"))
    .withConfig(QueryConfig.builder().withDatabase("neo4j").build())
    .execute()
    .records()
    .stream()
    .map(r -> r.get("name").asString())   // or: r.as(Person.class) — see note
    .findFirst()
    .orElseThrow();

// Using .as(Person.class) — maps RETURN keys to record fields by name
var person2 = driver.executableQuery("""
        MATCH (p:Person {name: $name})
        RETURN p.name AS name, p.age AS age
        """)
    .withParameters(Map.of("name", "Tom Hanks"))
    .withConfig(QueryConfig.builder().withDatabase("neo4j").build())
    .execute()
    .records()
    .stream()
    .map(record -> record.get("p").as(Person.class))
    .findFirst()
    .orElseThrow(() -> new RuntimeException("Person not found"));

public record Movie(String title, List<Person> actors) {}

var movieCypher = """
    MATCH (movie:Movie)
    LIMIT 1
    RETURN movie {
        .title,
        actors: COLLECT {
            MATCH (actor:Person)-[:ACTED_IN]->(movie)
            RETURN actor
        }
    }
    """;

var movie = driver.executableQuery(movieCypher)
    .withConfig(QueryConfig.builder().withDatabase("neo4j").build())
    .execute()
    .records()
    .stream()
    .map(r -> r.get("movie").as(Movie.class))
    .findFirst()
    .orElseThrow();

List<Map<String, Object>> rows = people.stream()
    .map(p -> Map.<String, Object>of("name", p.name(), "age", p.age()))
    .toList();

driver.executableQuery("UNWIND $items AS item MERGE (p:Person {name: item.name}) SET p.age = item.age")
    .withParameters(Map.of("items", rows))
    .withConfig(QueryConfig.builder().withDatabase("neo4j").build())
    .execute();

Config.builder()
    .withMaxConnectionPoolSize(50)
    .withConnectionAcquisitionTimeout(30, TimeUnit.SECONDS)
    .build()